RPOUT is a computer code for calculating the steady-state vertical distribution of radon progeny from ground level to one kilometre above the earth's surface. Given turbulent diffusivity, radon concentration, and attachment rate to aerosols, it provides prediction of both attached and unattached progeny. An option exists for including the effect of the earth's electric field. In addition to basic atmospheric science applications, in combination with radon progeny data, the code should be useful for studying dry deposition, a process important to removal of a number of atmospheric pollutants. The code can facilitate health physics estimates of radiation exposure to radon progeny at ground level as a function of meteorological conditions.